<template>
  <div class="box" style="height:500px">
    <div class="xtx-slider">
      <ul class="slider-body" @mouseenter="stopLoop" @mouseleave="startLoop">
        <li
          class="slider-item"
          v-for="(item, i) in sliders"
          :key="i"
          :class="{ fade: index === i }"
        >
          <img v-imgLazy="item.imgUrl" alt="" />
        </li>
      </ul>
      <div class="slider-indicator">
        <span :class="{active: index === i}"
         v-for="(item,i) in sliders"
         :key="i"
         @click="indicatorClick(i)"></span>
         <!-- index = i -->
      </div>
    </div>
  </div>
</template>

<script>
import { onMounted, onUnmounted, ref } from 'vue'
export default {
  name: 'XtxSlider',
  props: {
    sliders: {
      type: Array,
      default () {
        return []
      }
    },
    time: {
      type: Number,
      default: 1500
    }
  },
  setup (props) {
    //   保存当前点击的索引并给初始值
    const index = ref(0)
    // 保存计时器对象
    const timer = ref(null)
    // 实现自动播放 计时器
    function startLoop () {
      timer.value = setInterval(() => {
        index.value++
        // 判断如果索引大于数组长度 强制赋值为0
        if (index.value > props.sliders.length - 1) {
          index.value = 0
        }
      }, props.time)
    }
    // 清除计时器
    function stopLoop () {
      window.clearInterval(timer.value)
    }
    // 在dom渲染完后就调用自动播放
    onMounted(() => {
      startLoop()
    })
    // 组件销毁后清除定时器
    onUnmounted(() => {
      stopLoop()
    })
    // 点击小圆点
    function indicatorClick (i) {
      index.value = i
      stopLoop()
    }
    return {
      index,
      startLoop,
      stopLoop,
      indicatorClick
    }
  }
}
</script>

<style scoped lang='less'>
.xtx-slider {
  width: 100%;
  height: 100%;
  min-width: 300px;
  min-height: 150px;
  position: relative;
  .slider {
    &-body {
      width: 100%;
      height: 100%;
    }
    &-item {
      width: 100%;
      height: 100%;
      position: absolute;
      left: 0;
      top: 0;
      opacity: 0;
      transition: opacity 0.5s linear;
      &.fade {
        opacity: 1;
        z-index: 1;
      }
      img {
        width: 100%;
        height: 100%;
      }
    }
    &-indicator {
      position: absolute;
      left: 0;
      bottom: 20px;
      z-index: 2;
      width: 100%;
      text-align: center;
      span {
        display: inline-block;
        width: 12px;
        height: 12px;
        background: rgba(0, 0, 0, 0.2);
        border-radius: 50%;
        cursor: pointer;
        ~ span {
          margin-left: 12px;
        }
        &.active {
          background: #fff;
        }
      }
    }
    &-btn {
      width: 44px;
      height: 44px;
      background: rgba(0, 0, 0, 0.2);
      color: #fff;
      border-radius: 50%;
      position: absolute;
      top: 228px;
      z-index: 2;
      text-align: center;
      line-height: 44px;
      opacity: 0;
      transition: all 0.5s;
      &.prev {
        left: 20px;
      }
      &.next {
        right: 20px;
      }
    }
  }
  &:hover {
    .slider-btn {
      opacity: 1;
    }
  }
}
</style>
